Silvanus phillips thompson



(No Model.)

S. P. THOMPSON.

MAGNETO TELEPHONE. No. 389,500. Patented Apr. 6, 1886.r

c7? w MV Ilinrrnn Srnrns Partnr rauen SILVANUS PHILLIPS TIIOMPSON, OF UNIVERSITY COLLEGE, BRISTOL, ENGLAND.

MGNTf-TEL'EPHONE.

SPECIFICATION' forming pari: of Letters Patent No. 339,500, dated April G, 1886.

Application filed August 15, 1885. Serial No. l'lAJl. (No model.) Patented in England April 9, 1895, No. 4,423.

.To @ZZ whom, it may Concern.-

Be it known that I, SrLvnNus PHILLIPS THOMPSON, a subject of the Queen of Great Britain and Ireland, and residing at University College, Bristol, England, doctor of science and professor of experimental physics, have invented certain new and useful Improvements in llleetro-Telephonic Instruments, (for which I have applied for apatent in Great Britain on April 9, 1885, No. 4,4230 of which the following is a speciiication.

The object of my invention is to construct telephonie instruments very cheaply and of great power and efliciency, especially when used as receivers, although they may be used as transmitters, if desired.

According to myinvention I am enabled to dispense with the magnetic or mechanical restraint, which has hitherto been put upon the central portion ofthe diaphragms of these instruments, and I cause the variations inthe current due to the sound-waves to act upon movable pieces, forming part of a circuit independently magnctized and attached to an elastic but stift' body or spring of a nonmagnetic material, and carried in the box of the instrument by its sides or ends, so that its mid-portion is not under either mechanical or magnetic constraint. The coil or coils of the instrument is or are situated in proximity to the aforesaid movable pieces,which preferably take the form of two bent arms or levers, their outer ends being attach edtoward the opposite sides or ends of the aforesaid elastic and stiff body or spring and their inner ends having a space between them, forming a slight break in the magnetic circuit, the coil or coils preferably surrounding these ends which are in proximity to one another. Vhen an instrument thus constructed is in use as a receiver, the variations in the current due to the action of the sound-waves on a suitable transmitting apparatus passing in the coil or coils cause the movable pieces of the magnetic circuit to move toward and from one another, and these in turn act upon the opposite outward parts of the elastic and stiff body or spring to whichV they are attached, whereby the central portion is vibrated or moved in such amanner as to give good, clear, and powerful articulation in the instrument. y

In the drawings, Figure l is a section of an instrument constructed according to my invention. Figs. 2, 3, and I are similar views of modified forms, Fig. 5 being a perspective view of the arrangement shown in Fifr. 4, but with the cover moved.

In the several figures the parts are essentially the same and they are marked with the same letters of reference.

A is the box or case of the instrument in which is held the elastic or stiff body or spring B,Whicl1 may be of mica, ebonite,wood, brass, or other non-magnetic and elastic material. At or toward the sides or edges of this springpiece B pieces C are attached, the said pieces forming part of a magnetic circuit by reason of their being in proximity to the magnetized bar D, the said pieces C being preferably attached to the spring B, so that they can move independently of the main body of the magnet D, to which also the spring B may be attached, as shown. Around,but preferably not touching, the approximated ends of the pieces Gis fixed the coil E, in connection with the external wires. The only difference between the arrangements Figs. l and 2 is that in Fig. 2 the anis ofthe coil and the direction of the ends of the movable pieces C are at right angles to the position ol' those parts in the arrangement Fig. l.

In Fig. 3 the movable pieces are constituted by thin strips or additional pieces C2, fastened by screws to the parts C, attached to the spring B, instead of being formed by continuations of the same pieces, as in Figs. l and 2.

In Figs. 4 and 5 the main body of the magnet D is arranged as a ring, and it may be in halves separated by an insulating space or substance, the movable pieces C being affixed to the springin proximity tothe adj acont ends of like polarity, as shown clearly in Fig. 5.

In all eases it will be seen that there is no 'mechanical or magnetic constraint upon the I do not limit myself to the precise mechanical arrangement, shown in the examples given in the drawings, as it is evident that they may be varied without departing from the essential feature of my invention. For example, the magnetic circuit-pieces or anyT of them may be magnetized bya coil or coils, constituting them an electro-magnet, instead of their being permanently magnetized, as hereinbefore described.

I claiml. In atelephonic receiving or transmitting instrument, the combination, substantially' as hereinbefore set forth, of a non -magnetic elastic piece or spring for receiving or transmitting vibrations, supported at or near its edges and having its central portion unconstrained and free to vibrate, and movable magnetic pieces forming portions of a magnetic circuit secured thereto, substantially as llereinbefore described.

2. In a telephonie receiving Or transmitting instrument, the combination of an nncon` strained non-magnetic elastic piece or spring for receiving or transmitting vibrations, movablezmagnetic pieces forming portions of a magnetic circuit, and a surrounding coil or coils of Wire, substantially as hereinbefore described.

3. In a telephonie receiving or transmitting instrument, the combination, substantially as hereinbefore set forth, of the annular main body or core of the magnet situated in the upper portion of the case7 the non-magnetic diaphragm having its central portion free to vibrate, and the attached magnetic pieces.

In testimony WhereofI have signed my name to this specilication in tliepresence of two subscribing Witnesses.

SILVANUS PIII LLIPS THOMPSON.

XVitnesses:

I. XV. BARNARD,

6 Great James Si., Londen, lV. O. J. TUM'UER,

l0 .Denhgh Sl., London', S, 3L 

